The present invention relates generally to systems for generating gases for gas-actuatable devices. Dual stage inflators have been developed to provide staged gas production, whereby a first stage is actuated to deliver a predetermined amount of gas. If necessary, or if desired, a second stage is concurrently or subsequently actuated to deliver additional amounts of gas depending on the severity of an associated crash event, or depending on the position of the occupant, for example. As such, dual stage inflators typically contain two different combustion chambers that respond to a computer algorithm or other stimulus that directs one of several options for the dual stage inflator. For instance, the single stage or single chamber actuation of the dual stage inflator (in situations not requiring both stages) may be selected. Or, the concurrent actuation of both stages (in situations requiring additional gas) may be selected. Or, the sequential actuation of the two combustion chambers (depending on the position of the occupant for example) may be selected to tailor the inflation profile of the airbag.
One challenge is to ensure that the sympathetic ignition of a second chamber is prevented when the first chamber is algorithmically actuated to singularly operate. Or, alternatively, to ensure sequential actuation or operation of both chambers when that option is algorithmically determined. Stated another way, it is an ongoing challenge to prevent premature or sympathetic ignition of the secondary chamber prior to its scheduled deployment. In essence, it has been found that preventing the ignition and combustion products and heat from the primary or first-actuated chamber from entering or communicating with the second chamber is necessary to ensure independent operation of the first and second chambers.